Recently, there has been an increasing interest in energy storage technology. As the application field of energy storage technology is extended to mobile devices such as mobile phones, camcorders, laptop computers, and even medium and large size batteries in use for electric vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and electric vehicles (EV), the demand for high energy density of batteries used as a power source of electronic devices is growing. Lithium secondary batteries are the best battery which can meet the demand, and recently, many studies on them are being intensively made.
Currently, an electrode for use in a secondary battery is produced by coating a high concentration slurry on aluminum and copper foils, the high concentration slurry prepared by individually adding an electrode active material, a conductive agent, a binder and a solvent, and mixing them. The individual addition and mixing is because different characteristics are required for each lithium secondary battery product. However, the properties of the slurry significantly affect the electrode, so a mixing process of the slurry is a particularly important factor in producing the electrode.
Further, as a method of preparing an electrode active material slurry, a high viscosity mixing method may be used. This is a method which increases the viscosity a mixture of an electrode active material and a conductive agent to the maximum, adding excess solvents, and mixing them to prepare an electrode active material slurry, and has a disadvantage of reduced stability of the electrode active material slurry or wear of a mixer due to stress acting to the mixer.